This invention relates to medical apparatus, and more particularly to apparatus for use in making anastomotic connections between tubular body fluid conduits in a patient.
There are many medical procedures in which it is necessary to make an anastomotic connection between two tubular body fluid conduits in a patient. An anastomotic connection (or anastomosis) is a connection which allows body fluid flow between the lumen of the two conduits that are connected, preferably without allowing body fluid to leak out of the conduits at the location of the connection. As just one example of a procedure in which an anastomosis is needed, in order to bypass an obstruction in a patient""s coronary artery, a tubular graft supplied with aortic blood may be connected via an anastomosis to the coronary artery downstream from the obstruction. The anastomosis may be between the end of the graft and an aperture in the side wall of the coronary artery (a so-called end-to-side anastomosis), or the anastomosis may be between an aperture in the side wall of the graft and an aperture in the side wall of the coronary artery (a so-called side-to-side anastomosis (e.g., as in published Patent Cooperation Treaty (xe2x80x9cPCTxe2x80x9d) patent application WO 98/16161, which is hereby incorporated by reference herein in its entirety)). The graft may be natural conduit, artificial conduit, or a combination of natural and artificial conduits. If natural conduit is used, it may be wholly or partly relocated from elsewhere in the patient (e.g., wholly relocated saphenous vein or partly relocated internal mammary artery). Alternatively, no relocation of the graft may be needed (e.g., as in above-mentioned application WO 98/16161 in which a length of vein on the heart becomes a xe2x80x9cgraftxe2x80x9d around an obstruction in an immediately adjacent coronary artery). More than one anastomosis may be needed. For example, a second anastomosis may be needed between an upstream portion of the graft conduit and the aorta or the coronary artery upstream from the obstruction in that artery. Again, this second anastomosis may be either an end-to-side anastomosis or (as shown, for example, in above-mentioned application WO 98/16161) a side-to-side anastomosis. Alternatively, no second, upstream anastomosis may be required at all (e.g., if the graft is an only-partly-relocated internal mammary artery).
The currently most common technique for making an anastomosis is to manually suture the two tubular body fluid conduits together around an opening between them. Manual suturing is difficult and time-consuming, and the quality of the anastomosis that results is highly dependent on the skill of the person doing the suturing. In the case of coronary artery bypass procedures, one source of difficulty for suturing of an anastomosis may be motion of the heart. There is also increasing interest in procedures which are less invasive or even minimally invasive. Such procedures have potentially important advantages for patients, but they may increase the difficulty of performing manual suturing of an anastomosis by reducing or limiting access to the site within the patient at which the anastomosis must be made. Various examples of such less invasive or minimally invasive procedures are shown in above-mentioned application WO 98/16161, Goldsteen et al. U.S. Pat. No. 5,976,178, Sullivan et al. U.S. Pat. No. 6,120,432, published PCT patent application WO 98/55027, and Berg et al. U.S. patent application No. 09/187,364, filed Nov. 6, 1998, all of which are hereby incorporated by reference herein in their entireties.
In the case of making a conventional end-to-side anastomosis between a vein graft and the coronary artery, there are additional difficulties which may arise. First, the relative sizes of the coronary artery and the vein graft are different. For example, the coronary artery may typically have an inner diameter of about 1.0 to 3.0 mm, whereas a vein graft, such as the saphenous vein, may typically have an inner diameter of about 4 to 8 mm. This discrepancy between vessel diameters, i.e., a xe2x80x9ccaliber mismatch,xe2x80x9d may present a challenge to the physician to match the end of the relatively larger vein graft to an aperture in the side wall of the relatively smaller coronary artery. The resulting quality and amount of flow between the vein graft and the coronary artery, along with the provision of an effective hemodynamic seal between the two conduits, is often dependent upon the physician""s skill in making an effective junction between the two conduits.
Second, conventional end-to-side anastomosis typically joins the graft conduit to the coronary artery at an angle with respect to the lumen of the coronary artery, thus forming a junction at the wall of the coronary artery. Further away from this junction, the vein graft tends to lie against the heart structure, or substantially parallel to the lumen of the coronary artery. The transition of the vein graft from a substantially perpendicular juncture to the coronary artery to a substantially parallel position with respect to the coronary artery wall often occurs abruptly, which may result in kinking of the vein graft, with possibly reduced blood flow.
Third, joining vessels having relatively small diameters (e.g., 1-4 mm) presents the additional consideration of keeping the vessels open after the anastomosis has been made. It is therefore helpful to provide the anastomosis with a diameter equal to or larger than the diameter of the smaller vessel being joined. The larger anastomosis is performed in order to minimize the risk of closing off the flow due to the natural healing response. However, it is a challenge to provide a delivery system which is compatible with the dimensions of the anastomosis.
In view of the foregoing, it is an object of this invention to provide apparatus that can be used to make anastomotic connections in lieu of manual suturing.
It is another object of the invention to provide apparatus that can be used to make anastomotic connections even though access to the site of the anastomosis may be limited or even only indirect or remote.
It is still another object of the invention to provide apparatus that can be used to make anastomotic connections without the need for a high degree of manual suturing skill.
It is yet another object of the invention to provide apparatus for making anastomotic connections that is less adversely affected than manual suturing by adjacent or nearby body motion (e.g., motion of the patient""s heart).
It is a further object of this invention to provide apparatus for facilitating the making of higher quality anastomotic connections more rapidly and with more consistent results than is possible with prior art methods and apparatus such as manual suturing.
It is another object of the invention to provide apparatus for making a high quality anastomotic connection when joining two conduits having different relative diameters.
It is another object of the invention to provide apparatus for making a high quality anastomotic connection when joining two conduits having relatively small diameters.
It is another object of the invention to provide apparatus for making high quality anastomosis which allows the conduits to be positioned in a substantially flat configuration with respect to one another and which prevents kinking of the conduits.
An apparatus including a connector is provided to create an anastomosis between two conduits. A particular application of this invention is to join a saphenous vein graft (SVG) to a coronary artery in a side-to-side anastomosis. The connector structure has a first set of members that are used to secure the first conduit, typically the SVG, and a second set of members that engage the second conduit, typically the coronary artery.
The connector structure is mounted on a balloon catheter, which when pressurized, expands to a significant extent at the distal end thereof. The balloon enlarges the connector structure when positioned at the distal end portion of the balloon to create the anastomosis, and at the same time reduces the axial length of the connector, thereby compressing the first conduit to the second conduit, creating a hemodynamic seal and a firm attachment of the two conduits. After enlargement, the connector structure remains in place and adds structure to the anastomosis.
The second set of members is covered by a nosecone assembly to prevent trauma to the second conduit while the apparatus is being introduced. The nosecone assembly has a flexible structure which may change configuration to expose the second set of members after insertion into the second conduit and to allow removal of the nosecone after deployment.
The method for creating the anastomosis may comprise providing a connector and a delivery apparatus including an expansion balloon and a nosecone assembly. A next step may include making an aperture in the wall of the first conduit proximal to the distal end of the first conduit. The first conduit is then attached to the connector structure. More particularly, the first set of members of the connector structure may then pierce the wall of the first conduit. A locating ring, which may be colored with titanium dioxide, is placed about the first conduit adjacent the first set of members to provide an indication to the physician during delivery.
At the operative site, a second aperture is made in the second conduit wall. According to one embodiment, the second conduit may be cut and then dilated. The delivery system and the connector is introduced into the aperture in the second conduit. More particularly, the nosecone, in an introduction configuration, is inserted into the second conduit substantially axially to the lumen of the second conduit. The locating ring provides an indication that the first aperture in the first conduit is positioned adjacent the second aperture in the second conduit. The locating ring may provide a visual indication or a tactile indication when the locating ring is in contact with the wall of the second conduit.
The nosecone may then be changed to the removal configuration to uncover the second set of members. In an embodiment, the nosecone is a balloon structure which is inflated to uncover the second set of members. The nosecone assembly may be flexible, such that further advancement of the nosecone allows the nosecone to be positioned substantially parallel to the lumen of the second conduit. The delivery system may then be turned from a substantially axial position to a position at 90 degrees with respect to the lumen and the wall of the second conduit.
The balloon catheter is designed to allow significant expansion at its distal end portion. The connector, which has been positioned adjacent this distal end portion, may then be enlarged by expanding the balloon to make the anastomosis between the first and second conduits. More particularly, the connector structure enlarges radially and may shorten axially to approximate the first and second set of members of the connector, and thereby approximate the tissue of the first and second conduits to provide a seal, which is hemodynamic and has sufficient mechanical integrity and strength to provide durability. Once the connector structure is enlarged, the balloon and/or nosecone is deflated, and the delivery system may be removed and the first conduit may be ligated distal to the anastomosis without compromising the first conduit lumen.